The present invention pertains to containers in general, and particularly to containers for storing drinks or beverages. More particularly, the invention relates to a container wall structure provided with an operating element for opening the container by pushing in that operating element into the interior of the container.
Containers provided with operating elements to which external force, for example by a user's finger, is applied to release an opening through which a fluid stored in the container is poured out, are known in the art. In some of the known containers a separable or releasable opening region is provided in the container wall, which region is connected to the remaining portion of the container wall by a breaking edge extended along a score line. That breaking edge can be ruptured loose along said line by the external force applied to the operating element overlapping that opening region and pushed into the container whereby an opening is formed in the container wall; the operating element can be then slidably displaced relatively to the opening.
One of such containers is disclosed, for example, in U.S. Pat. No. 4,023,703 (FIGS. 48-53). In the disclosed container the circular opening region is located below the operating member having a semicircular end portion which merges into the hyperbolic portion and the parabolic portion. Force applied to the operating member for rupture of the opening region is transmitted to three separate locations, namely at the point of contact between the recess 276 and the downwardly-dished area 271, at the rivet connection and at the point where the score break dimple 278 contacts the operating member. It is important, however, to provide punctual force transmission from the operating member to the opening region of the container wall. Since containers under consideration are normally made out of sheet elastic metal punctual force transmission should be ensured so that the score line will be broken loose along its entire length.
If only partial rupture takes place it is necessary to use some auxiliary implements to break loose the remaining unbroken part of the score line because this is impossible to do by hand due to the fact that the line is concealed below the operating member which overlaps the opening region. Rupture of the opening region can be also obtained by an opening tab often provided on the operating member. In this case the opening region must be taken off from the container wall; this, however can cause injury of the user's finger. In a container described in the German patent publication DE-OS No. 23 41 077 the opening region of the wall remains in the container after rupture of the score line. This is also undersired, because it can lead to a waste product.
The disadvantage of the container disclosed in the both publications is that the opening formed in the container wall after rupture of the score line is not protected against the penetration of dirt, dust particles and insects into the container. Furthermore, if a container is dumped or put upside down the container's content flows out through that opening.
And finally, the score line, particularly in the structure shown on the U.S. Pat. No. 4,023,703 due to punctual force transmission can be ruptured by a relatively small pressure force applied onto the shearing projection; this can happen because the overlapping border of the operating member located against the opening region is not easily recognizable by a user, and, on the other hand, if coal acid-containing drinks are stored in the container the effect of coal acids escaping the container through the small break in the wall can make the container unsuitable for food storing.
In U.S. Pat. No. 4,023,703 (FIGS. 22-27) a tab is formed as a fully removable button provided with press-type connection means, snap-type connection means or threaded-type correction means. The disadvantage of this structure is that the button can not be tightly held in the container wall.
In the embodiment illustrated in FIGS. 48-53 of the U.S. patent under consideration tight reclosure of the exposed opening with the tab member is impossible because no controllable sealing is suggested in the reference and because two different ruptured opening regions must be taken into consideration.
U.S. Pat. No. 3,236,409 suggests another container wall construction in which a sheet metal plug has a metal tab fixed to the outside thereof. The disclosed structure also does not seem to be satisfactory because a plug totally separated from the opening stamped out from the container wall must be reinserted into that opening. If a container is formed of metal and coal-acid containing drinks are stored in that container such a structure has a drawback resided in that the cut edges of the opening are not protected against corrossive liquids. This lack of protection against corrosion leads to that the cut edges of the openings will be corroded in a very short period of time. The container's content poured out of the container and contacting those edges will be thus deteriorated.
The purpose of continuous connection of the opening region with the remaining portion of the container wall along the score line is that a continuous protective layer on the inner side of the container is ensured. Such a container, particularly its end or cover wall which is connected to the opening region by the score line has been subject of complex tests involving stress-measuring methods to determine whether the thickness of the protective layer was sufficient in all points of the score line. In the case if the cut edges the opening stamped out from the container wall are not coated with a new protection layer the tests performed proved that a container did not meet the standards and was found unsatisfactory.
Another conventional structure of the container has been disclosed in the European patent application 33,449. In that structure the openable closure member includes an opening tab provided on the container's cover, which tab can be inserted into the opening stamped out from the wall by rupturing the latter. This container is unsuitable for storing corrossive liquids either. In this container an additional score line is provided in the vicinity of the peripheral edge of the opening. In that case force transmission of external force applied via the closure member to the opening region is also different from that suggested in the present application.
The present invention has been designed to overcome disadvantages of conventional easy-openable containers of the type under consideration.